create intern! macro

Reviewed By: josephsavona

Differential Revision: D29374989

fbshipit-source-id: 2f343c036098ec52c92fd3aba0228eaf1ae683b9

compiler/crates/interner/Cargo.toml

@@ -9,5 +9,6 @@ license = "MIT"
 [dependencies]
 fnv = "1.0"
 lazy_static = "1.0"
+once_cell = "1.4"
 parking_lot = "0.10.2"
 serde = { version = "1.0.126", features = ["derive", "rc"] }

compiler/crates/interner/src/lib.rs

@@ -19,3 +19,8 @@ mod types;
 pub use bytes::{BytesKey, StringKey};
 pub use generic::InternTable;
 pub use types::{Intern, InternKey, RawInternKey};
+
+/// Re-exported values to be used by the `intern!` macro.
+pub mod reexport {
+    pub use once_cell::sync::Lazy;
+}

compiler/crates/interner/src/macros.rs

@@ -5,6 +5,24 @@
  * LICENSE file in the root directory of this source tree.
  */
 
+/// Interns the passed string literal and memoizes the result in a static
+/// variable. This can be used in performance sensitive code.
+/// ```
+/// use interner::intern;
+/// assert_eq!(intern!("example").lookup(), "example");
+/// ```
+#[macro_export]
+macro_rules! intern {
+    ($value:literal) => {{
+        use $crate::{reexport::Lazy, Intern, StringKey};
+        static KEY: Lazy<StringKey> = Lazy::new(|| Intern::intern($value));
+        *KEY
+    }};
+    ($_:expr) => {
+        compile_error!("intern! macro can only be used with string literals.")
+    };
+}
+
 /// Macro to implement an interner for an arbitrary type.
 /// Given `intern!(<Foo> as <FooKey>);`, this macro will implement the
 /// `Intern` trait for `<Foo>`, interning it a generated `<FooKey>` wrapper
@@ -26,7 +44,7 @@
 /// ```
 ///
 #[macro_export]
-macro_rules! intern {
+macro_rules! make_intern {
     ($name:ident as $alias:ident) => {
         use crate::{Intern, InternKey, InternTable, RawInternKey};
         use lazy_static::lazy_static;

compiler/crates/interner/src/tests.rs

@@ -41,7 +41,7 @@ fn test_custom_intern() {
         name: String,
     }
 
-    intern!(User as UserKey);
+    make_intern!(User as UserKey);
 
     let key: UserKey = User {
         name: "Joe".to_owned(),

compiler/crates/interner/src/types.rs

@@ -21,7 +21,8 @@ pub trait Intern: Eq + Hash + Clone {
 pub struct RawInternKey(NonZeroU32);
 
 impl RawInternKey {
-    pub(crate) fn new(value: NonZeroU32) -> Self {
+    #[inline(always)]
+    pub(crate) const fn new(value: NonZeroU32) -> Self {
         Self(value)
     }
 

compiler/crates/relay-schema/Cargo.toml

@@ -9,5 +9,4 @@ license = "MIT"
 [dependencies]
 common = { path = "../common" }
 interner = { path = "../interner" }
-lazy_static = "1.0"
 schema = { path = "../schema" }

compiler/crates/relay-schema/src/lib.rs

@@ -12,19 +12,12 @@
 #![deny(clippy::all)]
 
 use common::DiagnosticsResult;
-use interner::{Intern, StringKey};
-use lazy_static::lazy_static;
+use interner::intern;
 use schema::{ArgumentDefinitions, SDLSchema, TypeReference};
 use std::iter::once;
 
 const RELAY_EXTENSIONS: &str = include_str!("./relay-extensions.graphql");
 
-lazy_static! {
-    static ref DEFER_DIRECTIVE: StringKey = "defer".intern();
-    static ref STREAM_DIRECTIVE: StringKey = "stream".intern();
-    static ref LABEL_ARG: StringKey = "label".intern();
-}
-
 pub fn build_schema_with_extensions<T: AsRef<str>, U: AsRef<str>>(
     server_sdls: &[T],
     extension_sdls: &[U],
@@ -36,11 +29,11 @@ pub fn build_schema_with_extensions<T: AsRef<str>, U: AsRef<str>>(
 
     // Remove label arg from @defer and @stream directives since the compiler
     // adds these arguments.
-    for directive_name in &[*DEFER_DIRECTIVE, *STREAM_DIRECTIVE] {
+    for directive_name in &[intern!("defer"), intern!("stream")] {
         if let Some(directive) = schema.get_directive_mut(*directive_name) {
             let mut next_args: Vec<_> = directive.arguments.iter().cloned().collect();
             for arg in next_args.iter_mut() {
-                if arg.name == *LABEL_ARG {
+                if arg.name == intern!("label") {
                     if let TypeReference::NonNull(of) = &arg.type_ {
                         arg.type_ = *of.clone()
                     };